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Silicon carbide (SiC) has been extensively investigated in the last decade, specifically for applications in harsh environments. However, most SiC sensors require an external power supply, which cannot operate at high temperatures. This letter develops a new sensing technology in a SiC platform based on near field communication to eliminate the requirement for wired power sources. The 3C-SiC temperature sensors were fabricated from a SiC-on-insulator substrate formed by anodic bonding. The sensors functioned based on the thermoresistance of the SiC films with the high TCR of −13 000 ppm/K at 300 K and −3 000 ppm/K at 600 K. The resistance change of the sensors was wirelessly measured using a reading coil placed outside of the heating chamber, showing a significant resonant-frequency-shift (−400 ppm/K at 600 K) of the coupling impedance under temperature variation. The proposed technique is promising for the development of wireless wide-band-gap sensors used in extreme conditions.

In this letter, we report the photo-characteristics of an n-3C-Silicon carbide (SiC)/p-Si heterojunction under ultraviolet (UV) and visible illuminations. The 3C-SiC thin film has been grown on Si (100) substrate by a low pressure chemical vapor deposition technique at 1000 °C. The as-grown structure shows an excellent rectification ratio ( ${I}_{F}/{I}_{R}$ ) of $1.8\times 10^{6}$ at ±2 V and a reverse bias current of ${5.5}\times {10}^{-9}$ A at 2V in dark conditions. The heterojunction exhibits good sensitivity simultaneously to both UV (375 nm) and visible (637 nm) illuminations. The results indicate that the fabricated structure could be an excellent platform where detection of a wide spectral illumination is vital. The insight of electron-hole pairs generation and carrier transport mechanism at different illumination conditions is explained in detail via an anisotype heterojunction energy band diagram.

There is a growing interest and demand to develop sensors that operate at high temperatures. In this work, we investigate the temperature sensing properties of unintentionally doped n-type single crystalline cubic silicon carbide (SiC) for high temperatures up to 800 K. A highly sensitive temperature sensor was demonstrated with a temperature coefficient of conductivity (TCC) ranging from ${1.96}\times {10}^{4}$ to ${5.18}\times {10}^{4}$ ppm/K. The application of this material was successfully demonstrated as a hot film flow sensor with its high signal-to-noise response to air flow at elevated temperatures. The high TCC of the single crystalline SiC film at and above 800 K strongly revealed its potential for highly sensitive thermal sensors working at high temperatures.

This letter reports on the impact of compressive pressure on the electrical properties of carbon nanotube (CNT) yarns fabricated by dry Web-spinning and heat-treatment processes. Under increasing applied compressive pressure in the radial direction of the yarn, the electrical resistance of CNT yarns gradually decreased by 2.8% at a threshold applied pressure of 60 kPa where the resistance change is saturated. The decrease of CNT resistance with increasing pressure is attributed to the increase in the volume fraction of CNT, resulting in the increase of the effective junctions between adjacent CNTs, and the reduction of the tunneling distance between single CNTs. CNT yarns embedded in elastomers show high potential as an advanced functional element for a wide range of mechanical sensing applications including flexible pressure and tactile sensing.

We report a highly stable electrical conductance of a compact and well-oriented carbon nanotube yarn under tensile strain. The gauge factor of the yarn was found to be extremely small of approximately 0.15 thanks to the improvements in the dry spinning process, including multi-web spinning and heat treatment. The threshold strain $\varepsilon _{s}$ , below which the yarn retains its electrical conductance stability, has also been determined to be approximately $15\times 10^{3}$ ppm. Owing to its highly stable resistance under mechanical strain, the yarn has a good potential as a wiring material for niche applications, where light weight and resistance stability are required.

This letter presents for the first time the piezoresistive effect in p-type 4H–SiC. Longitudinal and transverse p-type 4H–SiC piezoresistors with a doping concentration of $10^{18}$ cm $^{-3}$ were fabricated along [ $1\overline {1}00$ ] directions. Ni/Al electrodes annealed at 1000 °C showed a good ohmic contact, and then, the longitudinal and transverse gauge factors were found to be as high as 31.5 and −27.3, respectively. The large gauge factors, attributed to the change of valance energy bands upon application of mechanical strain, and the linear relationship between the resistance change versus induced strain demonstrate the potential of p-type 4H–SiC for mechanical sensing applications.

This letter reports on the piezoresistive effect of top–down fabricated 3C-SiC nanowires (NWs). Focused ion beam was utilized to create p-type 3C-SiC NWs from a 3C-SiC thin film with a carrier concentration of $5 \times 10^{18}$ cm $^{-3}$ epitaxially grown on a Si substrate. The as-fabricated NWs were then subjected to tensile strains varying from 0 to 280 $\mu \varepsilon $ . Experimental data showed that the p-type 3C-SiC NWs possess a large gauge factor of 35, which is at least one order of magnitude larger than that of other hard materials, such as carbon nanotubes and graphene. This large gauge factor and the linear relationship between the relative resistance change and the applied strain in the SiC NWs indicate their potential for nanoelectromechanical systems sensing applications.

This letter reports for the first time the strain dependence of the offset voltage in p-type 3C-SiC van der Pauw square device. The p-type 3C-SiC thin film was epitaxially grown on a p-type Si(100) wafer using low pressure chemical vapor deposition followed by a conventional photolithography and dry etch processes, forming four-terminal van der Pauw device. The influence of applied tensile and compressive strain on the offset voltage of the van der Pauw device was investigated using the bending beam method. Experimental results showed that the offset voltage of the device is significantly changed by applied compressive and tensile strain, indicating the feasibility of using this effect for mechanical sensing applications. The sensitivity of the device to the applied strain has been found to be 70 (mV/A)/ppm.